diff --git a/Library/Homebrew/cmd/doctor.rb b/Library/Homebrew/cmd/doctor.rb
index 0a833add346d72691b5af2fc0c1018d59552635c..eff3743666793396db624c45009e98fab030e05b 100644
--- a/Library/Homebrew/cmd/doctor.rb
+++ b/Library/Homebrew/cmd/doctor.rb
@@ -620,6 +620,8 @@ def check_git_newline_settings
 end
 
 def check_for_autoconf
+  return if MacOS.xcode_version >= "4.3"
+
   autoconf = `/usr/bin/which autoconf`.chomp
   safe_autoconfs = %w[/usr/bin/autoconf /Developer/usr/bin/autoconf]
   unless autoconf.empty? or safe_autoconfs.include? autoconf
diff --git a/Library/Homebrew/formula_installer.rb b/Library/Homebrew/formula_installer.rb
index 9a480118423b20ea99dc651b995651094b4f73c9..486a4655fe13cff06c2a3c0a36425a06828c61e5 100644
--- a/Library/Homebrew/formula_installer.rb
+++ b/Library/Homebrew/formula_installer.rb
@@ -319,6 +319,8 @@ class FormulaInstaller
   end
 
   def check_m4
+    return if MacOS.xcode_version.to_f >= 4.3
+
     # Check for m4 files
     if Dir[f.share+"aclocal/*.m4"].length > 0 and not in_aclocal_dirlist?
       opoo 'm4 macros were installed to "share/aclocal".'